Sallyport - The Magazine of Rice University - Spring 2002

Through The Sallyport
Spring 2002
VOL.58, NO.3
Aurora Perilous
The term aurora borealis conjures up images of huge dazzling curtains,
streamers, and arches of atmospheric light that are beautiful and wondrous
to behold. It doesn t usually make us think of danger.
But, says Patricia Reiff, director of the Rice Space Institute and a professor
of astronomy and physics, the aurora borealis, or northern lights, and their
southern counterpart, the aurora australis, can pose definite problems.
Auroras are not simply visual displays; they are an electromagnetic
phenomenon. Reiff has been studying the auroras, which are an element of
space weather, in an effort to understand them and to be able to predict
their location, intensity, and effect.
Auroral light is emitted when electrons and protons that are trapped in
Earth s magnetic field excite atoms of gas in the upper atmosphere. The
east west aligned curtains of the auroras join to make complete rings around
both magnetic poles. At quiet times, the rings are dim and narrow and
tightly circle the poles. If the magnetic field is energized by an especially
strong bombardment of particles, such as during a solar storm, the auroral
rings brighten, thicken, and expand and can reach 2,500 miles in diameter
around each pole.
The brightest aurora, Reiff says, is associated with millions of amps of
electrical current, which has the potential to trip ground-based electrical
circuits and destroy transformers. The edge of the aurora closest to the pole
marks the danger zone. In particular, astronauts or high-altitude pilots who
fly poleward of the aurora can be endangered if the event in progress affects
their craft s electronic instruments or controls or if the auroral storm is
accompanied by an ongoing burst of solar cosmic rays.
Scientists at the Space Environment Laboratory in Boulder, Colorado, issue
space weather warnings about potentially dangerous auroras, but until
recently, they have been hampered by a lack of real-time eyes in space with
which to view auroral events. With the launch of the IMAGE spacecraft,
headed by James Burch 68 of Southwest Research Institute, real-time
monitoring of the auroras is finally being done. Using an instrument called
the Far Ultraviolet Imager, led by Steve Mende, who was a postdoc at Rice
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